1. Technical Field
The present invention relates to an electrostatic discharge (ESD) protection structure. More particularly, the present invention relates to an ESD protection structure formed on an active array substrate for a display device.
2. Description of Related Art
Liquid crystal display devices (LCDs) have been widely applied in various types of electronics. In the prior art, LCDs typically utilize amorphous silicon thin-film transistors (TFTs) as active elements. in general, the active array substrates of LCDs include electrostatic discharge (ESD) protection structures to prevent the elements and circuits on the active array substrates from damage due to electrostatic voltage surges. Usually, the ESD protection structures are fabricated during the manufacturing process of active array substrates. Therefore, in amorphous silicon TFT-LCDs, amorphous silicon semiconductor material is used in the ESD protection structure as well. However, the carrier mobility of the amorphous silicon semiconductor is unsatisfied, so that in many researches metal-oxide semiconductor material are promoted to replace the amorphous silicon semiconductor material. Unfortunately, metal-oxide semiconductor material exhibits unstable characteristics. For instance, the electrical performance is influenced by voltage stress, and lead to a shift in the threshold voltage of the metal-oxide semiconductor TFT. Similar problems occur in the ESD protection structures that use metal-oxide semiconductor material, and cause the instabilities of ESD protection structures. In view of the above, there exists in this art a need for an improved ESD protection structure that uses metal-oxide semiconductor material and provides greater electrical stabilities.